This is a multicenter, randomized, double-blind, placebo-controlled study of the efficacy, safety, and tolerability of subcutaneously administered Xolair as add-on therapy for the treatment of subjects aged 12-75 years old diagnosed with moderate to severe asthma who are inadequately controlled with high-dose inhaled corticosteroids (ICS)+ long-acting beta-agonists (LABA) with or without additional controller therapy.